Depends. Rendering the pages will always be done by the system CPU. The higher the resolution and color depth, the more work. Then, the interface connection takes its toll while transferring the data. Using USB over legacy parallel port is good since the former is on a fast chipset internal connection (or the PCI bus at least) rather than the slow legacy I/O appendix. For high volume laser printers, an Ethernet or USB 2.0 "high speed" connection is ideal. (NB: USB 2.0 "full speed" is nothing else but USB 1.x speed with a new badge.)